/**
 * Copyright 1996 self.com.au
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License. (http://www.apache.org/licenses/LICENSE-2.0)
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed 
 * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for 
 * the specific language governing permissions and limitations under the License.
 *
 * <dhamma-message src="Atisha (11th century Tibetan Buddhist master)">
 * 	The greatest achievement is selflessness. The greatest worth is self-mastery.
 * 	The greatest quality is seeking to serve others. The greatest precept is continual awareness.
 * 	The greatest medicine is the emptiness of everything. The greatest action is not conforming with the worlds ways.
 * 	The greatest magic is transmuting the passions. The greatest generosity is non-attachment.
 * 	The greatest goodness is a peaceful mind. The greatest patience is humility.
 * 	The greatest effort is not concerned with results. The greatest meditation is a mind that lets go.
 * 	The greatest wisdom is seeing through appearances. 
 * </dhamma-message>
 *
 * @author Ashin Wimalajeewa
 *
 * Note, this is a very old runtime library that I have evolved since 1996. I rarely use it
 * now because the Apache Commons project has made it obsolete.
 */
package self.util;

import java.util.*;

public class FifoMap implements Map {
	private static final long serialVersionUID = 1;

	private Map delegate;
	private int maxSize;

	private LinkedList putOrder = new LinkedList();

	public FifoMap(Map delegate, int maxSize) {
		this.delegate = delegate;
		this.maxSize = maxSize;
	}

	public Object put(Object key, Object value) {
		Object result = delegate.put(key, value);
		registerPut(key);
		if (size() > maxSize)
			delegate.remove(putOrder.removeFirst());
		return result;
	}

	public Object remove(Object key) {
		Object result = delegate.remove(key);
		registerRemove(key);
		return result;
	}

	public void clear() {
		delegate.clear();
		putOrder.clear();
	}

	protected void registerPut(Object key) {
		putOrder.remove(key);
		putOrder.addLast(key);
	}

	protected void registerRemove(Object key) {
		putOrder.remove(key);
	}

	public int size() {
		return delegate.size();
	}

	public boolean isEmpty() {
		return delegate.isEmpty();
	}

	public boolean containsKey(Object key) {
		return delegate.containsKey(key);
	}

	public boolean containsValue(Object value) {
		return delegate.containsValue(value);
	}

	public Collection values() {
		return delegate.values();
	}

	public void putAll(Map t) {
		delegate.putAll(t);
	}

	public Set entrySet() {
		return delegate.entrySet();
	}

	public Set keySet() {
		return delegate.keySet();
	}

	public Object get(Object key) {
		return delegate.get(key);
	}
}